The invention relates generally to systems for filtering particulate matter from hot gaseous mediums, and more particularly the invention relates to a ceramic tube filter array for high-temperature gas filtration.
The exhaust gases in industrial and utility cogeneration systems and fossil-based power generation plants entrain a large amount of particulate matter. Heretofore, porous ceramic filters have been used to remove the particulate matter from the hot exhaust gases. Such filters take the form of hollow, cylindrical tubes which are positioned in the exhaust system so that gases flow through the cylindrical walls to the center of the tubes and thence through a gas plenum to a clean gas exhaust. The ceramic tubes, or "candles,"are periodically cleaned by a reverse flow of gas which dislodges the particulate matter from the outside surfaces of the tubes. The particles fall to a bottom grating from which they are removed from the filter system.
In general, the manufacture of the rigid ceramic filter elements is limited to relatively short lengths due to shrinkage and warpage that can result during the final firing stage of manufacture. The application of these ceramic filter elements in large filter systems requires the packaging of a great number of individual elements to form filter modules. The cost effectiveness and technical viability of the commercial scale, high-temperature ceramic filter system is therefore dependent on developing a compact and technically workable design for mounting and sealing large numbers of individual filter elements.
U.S. Pat. No. 3,436,898 discloses a candle filter in which the filter tubes are arranged in a vertical casing divided by two horizontal partitions into three chambers. The lower chamber is the gas inlet chamber where the hot gases surround and enter the filter elements. In the middle chamber the purified gases leave the filter elements through the perforations in the spacer tubes and are withdrawn. The upper chamber is not entered by the hot gases, and contains springs protected from the heat of the gases for compressing the filter elements. This chamber is accessible from the outside.
U.S. Pat. No. 3,608,282 discloses filter apparatus comprising a first filter positioned within a housing, a closed annulus formed between the housing and the filter, a first conduit in open communication with a first surface of the filter, and closure means positioned in the first conduit. A second conduit is in open communication with a second surface the filter, and closure means is positioned in communication with the first surface of the filter.